The next round of the duelComputer must beat man at the game of Go

By: Katharina Bätz, English translation: Katrijn van Oudheusden

Lars Schäfers showing a state of a Go-game (Photo: Katharina Bätz)

Paderborn, Germany. The best chess players in the world are computers. More and more often they succeed at beating human elite players. What has come to seem so easy for computers in chess is still much more difficult in the popular Asian board game Go.
Human beings are still the winners in professional Go games. This should soon be a thing of the past, however: Since March 2009, researchers at the Paderborn Center for Parallel Computing (PC²) of the University of Paderborn, under the leadership of Prof. Dr. Marco Platzner, are working on achieving the playing strength of the best human players with a computer – and attempting to top it.

The calculation of good moves that corner human Go players is very difficult for a computer. In contrast to chess, where there are around 1043 possible moves, the possible amount of next moves in Go exceed 10170. Even for the fastest computers it is completely impossible to calculate all possible game variations.

To still be able to calculate an effective next move in a game, Lars Schäfers, researcher in PC², uses a so-called Monte-Carlo process. “The computer randomly generates and analyses a few hundred thousand next moves,” explains Schäfers. “Using probability, we can make educated guesses about a probable next good move,” he continues.

In the development process of a strong Go program, the project team makes good use of the capacities of PC2. There they have the option to use a super computer with the capacity of many hundreds of PCs, for a parallel search for the next best move. The computer needs to process as many random games as possible in the shortest amount of time. Additionally, the computer is allowed to learn game strategies on its own from a large database of transcribed professional Go games.

The goal of developing the world’s best Go program by March 2012, is an ambitious one. But the researchers of PC2 have demonstrated in the past that they are capable of successfully using computers to calculate difficult board games: Between 2003 and 2006, they helped develop the strongest chess computer at the time, called Hydra. In 2005, Hydra succeeded at beating the then fourth-placed chess player in the world ranking in an exciting match in London.

Working on the Microsoft-sponsored project in addition to Prof. Dr. Marco Platzner and Lars Schäfers, are: Dr. Ulf Lorenz from the TU Darmstadt, researchers of the Microsoft Research Lab in Cambridge, and many strong Go-players, the Paderborner Go Club among them.